After completing my last project, ( https://www.diyaudio.com/forums/digital-line-level/291645-building-soekris-dam1121-post5511258.html and https://www.diyaudio.com/forums/digital-line-level/291645-building-soekris-dam1121-post5573707.html ) with great help from many of you in this community, I’m starting with a scratch and a design by Broskie.
I want a simple design, without a big part list.
This is Broskies simple balanced phono preamp:
That can be found here:
Still More Phono Preamps
My simplistic mind brought to me that it would be just perfect, to use a 1:10 step up as Input transformer 12ax7 as gain tubes, ecc81 as cathode follower and as an output transformer a transformer voltage control, (by sowter with +6 and +12db tab) wich will give up to 1.225V wich is just what my power amp needs.
What do you think?
I want a simple design, without a big part list.
This is Broskies simple balanced phono preamp:
That can be found here:
Still More Phono Preamps
My simplistic mind brought to me that it would be just perfect, to use a 1:10 step up as Input transformer 12ax7 as gain tubes, ecc81 as cathode follower and as an output transformer a transformer voltage control, (by sowter with +6 and +12db tab) wich will give up to 1.225V wich is just what my power amp needs.
What do you think?
Mc with a 1:10 input trans and only one gain stage?
Think you need a step up as output transformer,
Reinhard
Think you need a step up as output transformer,
Reinhard
With an cartridge of 0,5mV
1:10 transformer -> 5mV
Ecc83 gain about 80 -> 400m
Cathode follower gain 0.9 -> 360mV
TVC with gain Tab +12db -> 1,4V
Not too bad is it?
Is the transformer not also getting 2x 360mV?
Lundahls LL1943 is a MC input with 1:16 or 1:32 wouldn’t that cover for the loss of the RIAA?
A second gain stage would mean many many more parts! :/
With 1:32 you get 10 dB more, not enough.
Redesign the cathode follers to a second diff-amp.
Reinhard
Redesign the cathode follers to a second diff-amp.
Reinhard
Or this more recent one maybe?
Return of the Triadtron & Balanced Phono Scroll down through the blog until you see the attached circuit. Would need an SUT. Might even be able to run balance right from the cart.
Steve
Return of the Triadtron & Balanced Phono Scroll down through the blog until you see the attached circuit. Would need an SUT. Might even be able to run balance right from the cart.
Steve
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Interesting. I plan to build a balanced phono pre this winter and was thinking of going with a 5755 zero-bias input stage.
I also want to do a transformer input setup but that gets expensive quickly even with a small signal transformer.
I also want to do a transformer input setup but that gets expensive quickly even with a small signal transformer.
What do you consider expensive in an SUT? Just curious? Would an entry level Lundhal for K&K Audio squeak into your budget. If not, I found some old Bogen T-157 microphone transformers on eBay that work OK. Not great but a good place to start.
Steve
Steve
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